Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 661
The Storm Prediction Center issued this mesoscale discussion at May 17, 2021, 8:34 PM CDT for 8 counties in Texas. It was in force for 116 min.
The area
The outline as issued.
The facts
- Issued
- May 17, 2021, 8:34 PM CDT (01:34 UTC)
- Expired
- May 17, 2021, 10:30 PM CDT
- In force
- 116 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 184
Counties Atascosa County, TX, Dimmit County, TX, Frio County, TX, La Salle County, TX, Maverick County, TX, McMullen County, TX, Webb County, TX, Zavala County, TX
The radar
The Laughlin AFB radar (KDFX), 120 km from the middle of the area, began a volume at 01:33 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Del Rio, TX (KDRT), launched 00:00Z, 1.6 hours before the alert went out and 162 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 3577 J/kg
- Mixed-layer CIN
- -91 J/kg
- Mixed-layer LCL
- 1068 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km storm-relative helicity
- 98 m²/s²
- 0-3 km storm-relative helicity
- 158 m²/s²
- Significant tornado parameter
- 1.5
- Supercell composite
- 6.5
The text
As transmitted.
460
ACUS11 KWNS 180134
SWOMCD
SPC MCD 180134
TXZ000-180330-
Mesoscale Discussion 0661
NWS Storm Prediction Center Norman OK
0834 PM CDT Mon May 17 2021
Areas affected...South Texas
Concerning...Severe Thunderstorm Watch 184...
Valid 180134Z - 180330Z
The severe weather threat for Severe Thunderstorm Watch 184
continues.
SUMMARY...The severe threat associated with a strong supercell
continues across south Texas, and additional development is possible
in the next 1-2 hours.
DISCUSSION...Regional radar and GOES IR trends over the past hour
continue to show a pair of robust supercells on either side of the
Rio Grande exhibiting strong rightward deviant motion as they move
to the south along the river. The environment in the vicinity of the
U.S. supercell remains supportive for organized convection with
nearly 4000 J/kg MLCAPE and nearly 50 knots of effective bulk shear.
An increase in MLCIN may hinder storm intensity to some degree over
the next hour, but the general expectation is for this storm to
persist into the late evening hours as it moves into southern
portions of WW 184 towards Laredo, TX. To the north, new convection
is developing along a confluence axis and may intensify over the
next one to two hours. There is some uncertainty regarding the
intensity and coverage of this new convection given increasing
inhibition and somewhat weak forcing for ascent, but the general
environment will remain supportive for a conditional severe threat
through 11 PM CDT.
..Moore.. 05/18/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CRP...EWX...BRO...
LAT...LON 29010083 29200013 29129897 28809828 28339814 27809860
27299909 27259957 27609998 28130046 28680086 29010083SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 17, 7:04 PM CDT | Mesoscale Discussion | SPC | Archer, Bosque, Brown, Clay, Comanche, Eastland and 15 more | 86 min |
| May 17, 7:23 PM CDT | Mesoscale Discussion | SPC | Carson, Dallam, Gray, Hansford, Hartley, Hemphill and 8 more | 2 hr |
| May 17, 7:32 PM CDT | Tornado Watch | SPC | Brown, Callahan, Coke, Coleman, Concho, McCulloch and 4 more | 3 hr |
| May 17, 7:37 PM CDT | Mesoscale Discussion | SPC | Callahan, Coke, Coleman, Glasscock, Howard, Jones and 6 more | 83 min |
| May 17, 8:04 PM CDT | Severe Thunderstorm Watch | SPC | Archer, Clay, Comanche, Eastland, Erath, Hamilton and 11 more | 5 hr |
| May 17, 9:28 PM CDT | Mesoscale Discussion | SPC | Carson, Collingsworth, Donley, Gray, Hansford, Hemphill and 7 more | 2 hr |
| May 17, 9:44 PM CDT | Mesoscale Discussion | SPC | Armstrong, Borden, Briscoe, Childress, Collingsworth, Cottle and 15 more | 91 min |
| May 17, 10:23 PM CDT | Mesoscale Discussion | SPC | Archer, Brown, Callahan, Clay, Coke, Coleman and 16 more | 97 min |
| May 17, 10:35 PM CDT | Mesoscale Discussion | SPC | Andrews, Borden, Brewster, Crane, Crockett, Dawson and 13 more | 85 min |
| May 17, 10:58 PM CDT | Severe Thunderstorm Watch | SPC | Andrews, Borden, Brown, Coke, Coleman, Concho and 22 more | 7 hr |
| May 17, 11:37 PM CDT | Mesoscale Discussion | SPC | Bosque, Brown, Comanche, Denton, Eastland, Erath and 9 more | 83 min |
| May 18, 1:02 AM CDT | Mesoscale Discussion | SPC | Brooks, Duval, Jim Hogg | 58 min |
| May 18, 1:29 AM CDT | Mesoscale Discussion | SPC | Coke, Concho, Crane, Crockett, Ector, Glasscock and 13 more | 91 min |
| May 18, 5:07 AM CDT | Mesoscale Discussion | SPC | Coke, Concho, Irion, Reagan, Runnels, Schleicher and 2 more | 53 min |
| May 18, 1:18 PM CDT | Mesoscale Discussion | SPC | Atascosa, Austin, Bastrop, Bexar, Brazos, Burleson and 28 more | 117 min |
| May 18, 1:57 PM CDT | Mesoscale Discussion | SPC | Bailey, Castro, Deaf Smith, Parmer, Randall, Swisher | 3 hr |
| May 18, 2:29 PM CDT | Tornado Watch | SPC | Anderson, Atascosa, Austin, Bastrop, Bexar, Blanco and 30 more | 7 hr |
| May 18, 2:30 PM CDT | Mesoscale Discussion | SPC | Bowie, Camp, Cass, Cherokee, Franklin, Gregg and 12 more | 2 hr |
| May 18, 3:51 PM CDT | Severe Thunderstorm Watch | SPC | Bowie, Camp, Cass, Cherokee, Franklin, Gregg and 11 more | 5 hr |
| May 18, 3:52 PM CDT | Mesoscale Discussion | SPC | Bastrop, Caldwell, Colorado, Fayette, Gonzales, Guadalupe and 2 more | 83 min |
| May 18, 5:10 PM CDT | Mesoscale Discussion | SPC | La Salle, McMullen, Webb | 95 min |
| May 18, 5:39 PM CDT | Mesoscale Discussion | SPC | Bowie, Cass, Gregg, Harrison, Marion, Morris and 1 more | 2 hr |
| May 18, 6:07 PM CDT | Mesoscale Discussion | SPC | Armstrong, Borden, Briscoe, Carson, Castro, Cochran and 17 more | 113 min |
| May 18, 6:13 PM CDT | Mesoscale Discussion | SPC | Austin, Brazos, Burleson, Colorado, DeWitt, Fayette and 14 more | 92 min |
Nearby
Mesoscale Discussions in Texas, 2021Every mesoscale discussion in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.